Transparent Artificial Soil as a Medium for Root Phenotyping and Plant-Bacteria Studies

Often used in plant growth studies, root phenotyping is an essential technique to understand plant development in response to varying conditions. This technique is also used to evaluate the benefits of plant growth-promoting (PGP) bacteria on plant growth over time. Traditional phenotyping methods in regular soil often require uprooting, which can damage root structures and limit longitudinal studies. Using regular soil also reduces control over the conditions or nutrients in which the plants develop. One potential solution to these problems is transparent artificial soil, a medium that facilitates non-destructive root phenotyping. Using transparent artificial soils enables researchers to observe root systems in situ over time, reducing disturbance and allowing developmental root studies of the same organism. It can also maintain and give the necessary nutrients for root development. Our aim is to research and optimize a transparent soil recipe and fabrication process to enhance the reproducibility and accessibility of our plant-microbe interaction studies. Transparent beads were created by adding an alginic acid:gellan gum mixture to magnesium chloride, creating spherical gel beads. The success of the beads for root phenotyping was evaluated by comparing the growth of Arabidopsis thaliana in regular soil versus artificial soil. Artificial soil containing the PGP rhizobacteria Variovorax was also evaluated for its success in promoting plant growth in these new conditions. The recipe and technique we developed through this project are crucial to advancing non-invasive root imaging methods, offering a valuable tool for studying plant-microbe interactions and root system dynamics for future experiments.